Bar code scanners are used in a wide variety of applications, such as retailing, inventory control, customer identification and many other applications. Many bar code scanners are adapted to scan a bar code located on an object, when the object is placed within the field of view of the scanner. Many such scanners produce complex scan patterns in order to maximize coverage of an object, so that a bar code located on an object will produce a readable reflection, even if the bar code is located on a relatively obscure area of an irregularly shaped object.
Frequently, especially in retail settings, it is highly desirable to scan objects in a rapid fashion, with objects being scanned one after another at a rate of more than one object every two seconds. At times during the scanning of a succession of objects, the scanning of some of the objects may be impaired for any of a number of reasons. For example, missed scans may occur due to a failure of an operator to bring the bar code into the field of view of the scanner. Double scans may result from the scanning of the same bar code by different scan lines. A scan of a bar code may fail because of low legibility resulting, for example, from low contrast of the bar code or damage to the bar code. Incorrect placement of a bar code on an object may result in an incorrect identification of the product being entered into the transaction.